Here$$s a complete implementation in C$++$ that fulfills your requirements.

### Explanation of Key Components:

$1.**$Input Validation$**$:

$-$ Ensures the number of records to process is within the valid range $(8$ to $90).$

$2.**$File Handling$**$:

$-$ Opens the file $`$indataH$01`$ and reads names and grades into arrays.

$3.**$Calculation$**$:

$-$ Computes the average of the grades using a loop.

$4.**$Output$**$:

$-$ Displays each student's name, grade, and classification $($below average, average, or above average$).$

This program adheres strictly to the guidelines and uses arrays, loops, and functions effectively to handle the task.